Things You'll Need
Instructions
Insert one end of the Game Boy Advance-to-GameCube extension cable into the expansion slot on the Game Boy Advance.
Connect the other end of the Game Boy Advance-to-GameCube extension cable into one of the GameCube controller inputs on the top of the Nintendo Wii. The GameCube controller inputs are beneath a small door on the top of the Wii console.
Turn on the Wii and insert a GameCube game that is compatible with the Game Boy Advance. Compatible games will list this functionality on their cases.